Migration issue with Single Table Inheritance from JPA to hibernate

When migrating from standard JPA (EclipseLink) to hibernate, tests are failing due to improper number of child records and/or invalid types for child objects. I think the issue is the SQL generated by hibernate is not using the discriminator column in the where clause on an InheritanceType.SINGLE_TABLE relationship.

Any suggestions on what to change in the mappings?

Thanks in advance,

Timothy

Environment

• postgres 9.6.17
• spring boot / JPA 2.4.0
• postgres mvn dependency 42.2.18

Domain background

A DcMotor may have up to 2 sets of wires. Represented in the entity each in its own List. These wires are of either ARM or EQ type. Since the attributes on the wires are the same, a single table was chosen by the DBA with a discriminator column named coil_type with values of either ARM or EQ.

Class definitions

Parent Entity

@Entity 
@Table(name = "dc_motor")
public class DcMotor implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Version
    private Integer version;
  //other direct fields

    @OneToMany(orphanRemoval = true, cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JoinColumn(name = "motor_id", referencedColumnName = "id", nullable = false)
    @OrderColumn(name = "idx")
    private List<WireArm> armWires;

    @OneToMany(orphanRemoval = true, cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JoinColumn(name = "motor_id", referencedColumnName = "id", nullable = false)
    @OrderColumn(name = "idx")
    private List<WireEq> eqWires;

Abstract base class for WireArm and WireEq

@Entity 
@Table(name = "dc_wire")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "coil_type", length = 10, discriminatorType = DiscriminatorType.STRING)
public abstract class DcWire implements IDcWire {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    // other direct fields
    // discriminator column coil_type is not explicitly listed as a field

Concrete child class

@Entity
@DiscriminatorValue(value = "ARM")
public class WireArm extends DcWire implements IDcWire {
    // just constructors
}

@Entity
@DiscriminatorValue(value = "EQ")
public class WireEq extends DcWire implements IDcWire {
    // just constructors
}

SQL generated

select /*all fields*/ from dc_motor dcmotor0_ where dcmotor0_.id=1;
select /* all fields EXCEPT coil_type*/ from dc_wire armwires0_ where armwires0_.motor_id=1;
select /* all fields EXCEPT coil_type*/ from dc_wire eqwires0_ where eqwires0_.motor_id=1;